1. Field of the Invention
The present invention relates to methods and systems for protection and tracking use of computer software. More specifically, the invention relates to identifying software for protection and tracking purposes by deriving a characteristic signature from the software.
2. Description of Related Art
Various methods are known in the art for preventing unauthorized duplication and use of software and other copyrighted digital content. While most such methods are at least partially effective in preventing piracy, many copyright software methods can be defeated by the persistent efforts of skilled individuals—sometimes called “hackers”—with expertise in computer systems and programming. Such hackers are sometimes able to modify distributed copies of software to disable its copyright protection features, so that the modified software can be freely copied or used without license restrictions, while still retaining its essential functionality. Software in which protection features are thusly disabled is sometimes referred to as being “cracked.”
The existence of cracked software versions may create a risk of unauthorized or illegal distribution and use, which may harm legitimate software providers. Besides causing loss of licensing revenue, cracked software versions may not function as originally designed, which may harm user's perception of the software provider's quality control. For these and other reasons, it is desirable to detect and prevent the spread of cracked software or other digital content. Current methods for detecting and preventing the spread of cracked software include human monitoring of software distribution channels to detect and track illegally modified software versions. However, such monitoring is relatively expensive and inefficient, and may not provide sufficient (or any) control over use of cracked software even after it is detected. It is therefore desirable to provide improved methods for detecting and controlling distribution and use of software or other digital content that has been tampered with, such as by removing copyright protection features.